Screening performance of K6/K10 and other screening instruments for mood and anxiety disorders in Japan

Aims: This study aimed to establish the screening performance and optimal cut-off points for the Japanese version of Kessler (K) 6, K10 and the Depression and Suicide Screen (DSS). Methods: A self-report questionnaire including K6, K10 and DSS, as well as the Center for Epidemiologic Studies - Depression Scale (CES-D), was administered to a random sample of community residents in Japan (non-cases, n = 147) and psychiatric outpatients diagnosed with mood or anxiety disorders according to DSM-IV (cases, n = 17). A receiver-operator characteristics (ROC) curve was drawn to estimate the area under the curve (AUC), the sensitivity, and specificity with the optimal cut-off points for K6, K10, and DSS, which were then compared with those of CES-D. The community sample was also asked to rate each measure on a scale from 'very easy' to 'very hard' to use. Results: K6 and K10 showed a high AUC (0.93-0.94), which was comparable to that of CES-D(0.95), but DSS showed a significantly smaller AUC (0.89) than CES-D (P < 0.05). The optimal cut-off points were estimated as 4/5 for K6, 9/10 for K10, and 1/2 for DSS. The sensitivity of these three scales was similar, but the specificity was lower for DSS than for the other two. K6, K10 and DSS were rated as being 'very easy' or 'easy to use' significantly more than CES-D (P < 0.01). Conclusion: The screening performance of the Japanese versions of K6 and K10 was comparable with that of CES-D, and better than that of DDS. K6/K10, particularly K6, might have an advantage, even over the CES-D, because of its similar screening performance and better acceptability.